30 



BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



Body moderately robust anteriorly, tapering posteriorly; its depth 

 at origin of first dorsal 5.5 to 6.5 in length anterior to base of upper 

 lobe of caudal; caudal peduncle very slender, its least depth 5.5 to 6.3 

 in head to first gill slit; head much depressed, its depth over middle of 

 eyes about equal to width of mouth, its length to first gill sUt 4.2 to 

 4.6 in length anterior to base of upper lobe of caudal; snout rather 

 pointed, 2.1 to 2.3 in head, its preoral length only a little greater than 

 width of mouth, 2.8 to 3.0 in head; eye quite elongate, 7.6 to 8.0; 

 mouth rather narrow, its width at angles scarcely as great as space 

 between outer margins of nostrils, 2.9 to 3.3 in head; labial folds 

 present, the upper one longer and broader than the lower, the width of 

 lower one not more than a third the distance to symphysis; teeth 

 flat and smooth, without cusps; dermal dentacles with a moderately 



Figure 5. — MusUlus mento Cope. From the type of M. abhotti Evermann and Radcliffe, 

 550 mm. long, La Ventanilla, Peru (U.S. N.M. No. 7769^). Insert, ventral view of head. 

 (After Evermann and Radcliffe, 1917.) 



prominent median keel and generally with one and occasionally with 

 two on each side (more prominent in specimens examined by me than 

 shown by Bigelow and Schroeder, 1940, pL 19, fig. C); first dorsal 

 originating over or more usually somewhat behind midlength of pec- 

 toral, greatest height of fin (without thick base) generally about 

 equal to width of head over eyes, the distal margin a little concave, 

 with a sHghtly produced posterior lobe; predorsal length 2.6 to 3.0 

 in length anterior to base of upper lobe of caudal; distance between 

 dorsals 4.6 to 5.1; second dorsal similar in shape though smaller than 

 the first, its origin rather far behind vertical from distal margin of 

 ventral; upper lobe of caudal moderately broad, with an oblique outer 

 margin sometimes nearly as wide as interorbital space, entire length 

 of lobe 4.2 to 4.7 in length anterior to its base, lower lobe distinct and 

 long, with slightly concave outer margin, about as long as snout and 

 eye; anal small, its origin about under middle of second dorsal, 3.0 

 to 3.5 in head; ventral inserted rather more than an eye's diameter 



